1. Field of the Invention
The present invention relates to an apparatus and a method for detecting abnormalities of a linear solenoid valve for regulating a control oil pressure that is supplied to a hydraulic device based on a control signal (an electric signal). The invention relates more particularly to an apparatus and a method for detecting abnormalities of a hydraulic device having a frictional engagement element such as a hydraulically actuated clutch or brake adapted to be brought into engagement upon receipt of an oil pressure force and a linear solenoid valve for regulating an actuation control oil pressure that is supplied to the frictional engagement element.
2. Description of the Related Art
A hydraulic device is used as, for example, a transmission in an automotive automatic transmission or the like, and in general, the transmission is constructed so as to automatically control speed changes according to the opening of an accelerator and the vehicle speed. The transmission for performing such automatic speed changes is constructed to have gear trains constituting a plurality of power transmission paths, and the gear trains are automatically changed over to select any of the power transmission paths by controlling the engagement of frictional engagement elements (a hydraulic clutch, brakes and the like), whereby the speed change control is implemented. In a known engagement control of a frictional engagement element, the control is performed by controlling the supply of working oil pressure (engagement control oil pressure), and in many cases a solenoid valve is used to control the supply of working oil pressure in an electric fashion. In this case, since the malfunction of the solenoid valve results in a failure of change-speed control, it is important to detect abnormalities of the solenoid valve. For example, JP-A-2000-266176 discloses an apparatus for detecting abnormalities of a solenoid valve.
In recent automatic transmissions, in many cases, controlling the regulation of engagement control oil pressure is implemented by a linear solenoid valve. In a case where a linear solenoid valve is used to implement controlling the engagement of a frictional engagement element to thereby perform change-speed controlling, it is possible to freely regulate an engagement control oil pressure which is supplied to the frictional engagement element by controlling energizing of the linear solenoid valve, and this provides an advantage that the degree of freedom in setting an engagement control oil pressure at the time of changing speeds becomes large. However, in case there occurs an abnormality in the linear solenoid valve, it becomes impossible to control the regulation of change-speed control oil pressure, this causing a problem that the change-speed control becomes imprecise. Owing to this, conventionally, an oil pressure sensor for measuring an engagement control oil pressure outputted from the linear solenoid valve is mounted on a change-speed control device externally, and an engagement control oil pressure outputted from the linear solenoid valve relative to a control signal inputted into the linear solenoid valve is detected with the hydraulic sensor to thereby detect the existence of abnormalities of the linear solenoid valve.
Incidentally, in an automatic transmission, there is no need to use an oil pressure sensor, and in general there is mounted no oil pressure sensor, and therefore, every time an abnormality detection is implemented, an oil pressure sensor is mounted externally on the automatic transmission to detect abnormalities of the linear solenoid valves, this causing a problem that abnormality detection can be carried out only at limited places such as plants and dealerships. In addition, oil pressure sensors are expensive, and this causes a problem that there is provided an expensive abnormality detector. Furthermore, there is caused a problem that there is a risk of dust or foreign matters entering the hydraulic device when the oil pressure sensor is attached to and detached from the same device.
The invention was made in view of the above problems and an object thereof is to provide an apparatus and a method for detecting abnormalities of a linear solenoid valve and a hydraulic device using the linear solenoid valve with ease. In particular, an object of the invention is to provide an apparatus and a method for detecting abnormalities of a linear solenoid valve and a hydraulic device using the linear solenoid valve by having a hydraulic switch which is inexpensive and is equipped within an oil pressure controller of an automatic transmission in many cases.
With a view to attaining the objects, according to an aspect of the invention, there is provided an apparatus for detecting abnormalities of a linear solenoid valve comprising a linear solenoid valve (for example, first to third linear solenoid valves 51, 52, 53 in an embodiment) for regulating a control oil pressure that is supplied to a hydraulic device (for example, a second clutch 12, a third clutch 13 in the embodiment) based on a control signal, a hydraulic switch (for example, first and second hydraulic switches 61, 62 in the embodiment) set to be switched on and off when an oil pressure variation is applied thereto which overpasses a predetermined switching oil pressure, and a valve actuating controller (for example, an electronic control unit 60, an external diagnosis unit 70 or the line in the embodiment) for sending out the control signal to the linear solenoid valve, wherein the hydraulic switch is disposed in such a manner as to receive the control oil pressure that has been regulated by the linear solenoid valve. A control signal is sent from the valve actuating controller to the linear solenoid valve to increase the control oil pressure from a predetermined lower pressure which is lower than the switching oil pressure to a predetermined higher pressure which is higher than the switching oil pressure to thereby cause the linear solenoid valve to regulate the control oil pressure, during which, when the hydraulic switch is switched on and off a pressure-increased side signal oil pressure is detected which corresponds to the control signal outputted from the valve actuating controller. And, a control signal is sent from the valve actuating controller to the linear solenoid valve to decrease the control oil pressure from the predetermined higher pressure to the predetermined lower pressure to thereby cause the linear solenoid valve to regulate the working oil pressure, during which, when the hydraulic switch is switched on and off a pressure-decreased side signal oil pressure is detected which corresponds to the control signal outputted from the valve actuating controller. Further, the linear solenoid valve is diagnosed as being abnormal when a difference between the pressure-increased side signal oil pressure and the pressure-decreased side signal oil pressure exceeds an abnormality determination value.
In addition, according to another aspect of the invention, there is provided a method for detecting the existence of an abnormality of a linear solenoid valve for regulating a control oil pressure that is supplied to a hydraulic device based on a control signal using a hydraulic switch disposed at a position to receive the control oil pressure which has been regulated by the linear solenoid valve and set to be switched on and off when an oil pressure variation is applied thereto which overpasses a predetermined switching oil pressure, and the method comprises the steps of, firstly, sending a control signal to the linear solenoid valve to increase the control oil pressure from a predetermined lower pressure which is lower than the switching oil pressure to a predetermined higher pressure which is higher than the switching oil pressure, while the above step is being implemented, detecting a pressure-increased side signal oil pressure which corresponds to the control signal resulting when the hydraulic switch is switched on and off upon receipt of the control oil pressure which has been regulated by the linear solenoid valve, sending a control signal to the linear solenoid valve to decrease the control oil pressure from the predetermined higher pressure to the predetermined lower pressure, while the above step is being implemented, detecting a pressure-decreased side signal oil pressure which corresponds to the control signal resulting when the hydraulic switch is switched on and off upon receipt of the control oil pressure which has been regulated by the linear solenoid valve, and diagnosing that the linear solenoid valve is abnormal when a difference between the pressure-increased side signal oil pressure and the pressure-decreased side control oil pressure exceeds an abnormality determination value.
The hydraulic switch is switched on and off when the engagement control oil pressure varies in such a manner as to overpass the switching oil pressure both when the engagement control oil pressure varies to increase and when the engagement control oil pressure varies to decrease, and even in consideration of a control response delay, the difference between the first pressure-increased side signal oil pressure and the first pressure-decreased side signal oil pressure must be small. Namely, with the difference being large, it is determined that the linear solenoid valve is being abnormal. According to the invention, the detection of abnormalities of the linear solenoid valve is implemented based on such a determination, and according to the apparatus and method for detecting abnormalities of the linear solenoid as described above, the existence of abnormalities of the linear solenoid valve can be detected easily by using the relatively inexpensive hydraulic switch (without using an oil pressure sensor for detecting the value of an oil pressure).
According to a further aspect of the invention, there is provided an apparatus for detecting abnormalities of a hydraulic device comprising a frictional engagement element (for example, a LOW clutch 11, a second clutch 12, a third clutch 13, a fourth clutch 14, a fifth clutch 15 or the like in the embodiment) adapted to be brought into engagement upon receipt of an oil pressure force, a linear solenoid valve (for example, the first to third linear solenoid valves 51, 52, 53 in the embodiment) for regulating an engagement control oil pressure which is supplied to the frictional engagement element, a hydraulic switch (for example, the first and second hydraulic switches, 61, 62 in the embodiment) set to be switched on and off when an oil pressure variation is applied thereto which overpasses a switching oil pressure which is an engagement control oil pressure at which the frictional engagement element starts to be brought into engagement and a valve actuating controller (for example, the electronic control unit 60, the external diagnosis unit 70 or the like in the embodiment) for controlling the actuation of the linear solenoid valve so as to make the linear solenoid valve implement the regulation of the engagement control oil pressure, wherein the hydraulic switch is disposed in such a manner as to receive the control oil pressure that has been regulated by the linear solenoid valve, wherein a control signal is sent from the valve actuating controller to the linear solenoid valve to increase the engagement control oil pressure from a predetermined lower pressure which is lower than the switching oil pressure to a predetermined higher pressure which is higher than the switching oil pressure to thereby cause the linear solenoid valve to regulate the engagement control oil pressure, during which, when the hydraulic switch is switched on and off a first pressure-increased side signal oil pressure is detected which corresponds to the control signal outputted from the valve actuating controller, and wherein a control signal is sent from the valve actuating controller to the linear solenoid valve to decrease the engagement control oil pressure from the predetermined higher pressure to the predetermined lower pressure, during which, when the hydraulic switch is switched on and off a first pressure-decreased side signal oil pressure is detected which corresponds to the control signal outputted from the valve actuating controller, whereby the linear solenoid valve is diagnosed as being abnormal when a difference between the first pressure-increased side signal oil pressure and the first pressure-decreased side control oil pressure exceeds a first abnormality determination value.
With the abnormality detecting apparatus constructed as described above, the existence of abnormalities of the linear solenoid valve can be detected easily by using the relatively inexpensive hydraulic switch (without using an oil pressure sensor for detecting the value of an oil pressure). In addition, in many cases, the hydraulic switch is provided on the hydraulic device such as a change-speed control valve in an automatic transmission, and as this occurs, it is possible to construct such that the detection of abnormalities can be implemented easily without requiring the selection of a place by using the hydraulic switch.
According to another aspect of the invention, the apparatus for detecting abnormalities is provided with an engagement detection unit (for example, the electronic control unit 60 adapted to be actuated upon receipt of a detection signal from an engine speed sensor 65 in the embodiment) for detecting an engagement of the frictional engagement element, wherein a control signal is sent from the valve actuating controller to the linear solenoid valve to increase the engagement control oil pressure from the predetermined lower pressure to the predetermined higher pressure to thereby cause the linear solenoid valve to regulate the frictional engagement control oil pressure, during which a second pressure-increased side signal oil pressure resulting when the engagement of the frictional engagement element is started is detected by the engagement detection unit, whereby the hydraulic switch may be diagnosed as being abnormal when a difference between the first pressure-increased side signal oil pressure and the second pressure-increased side signal oil pressure exceeds a second abnormality determination value.
According to a further aspect of the invention, the apparatus for detecting abnormalities is provided with an engagement detection unit for detecting an engagement of the frictional engagement element, wherein a control signal is sent from the valve actuating controller to the linear solenoid valve to decrease the engagement control oil pressure from the predetermined higher pressure to the predetermined lower pressure to thereby cause the linear solenoid valve to regulate the frictional engagement control oil pressure, during which a second pressure-decreased side signal oil pressure resulting when the release of the frictional engagement element is started is detected by the engagement detection unit, whereby the hydraulic switch is diagnosed as being abnormal when a difference between the first pressure-decreased side signal oil pressure and the second pressure-decreased side signal oil pressure exceeds a third abnormality determination value.
The hydraulic switch is set to use as the switching oil pressure the engagement control oil pressure at which the engagement of the frictional engagement element is started, and as described above, in the event that the difference between the first pressure-increased side signal oil pressure and the second pressure-increased side signal oil pressure exceeds the second abnormality determination value, or in the event that the difference between the first pressure-decreased side signal oil pressure and the second pressure-decreased side signal oil pressure exceeds the third abnormality determination value, it is considered that an abnormality is being caused such as the set switching oil pressure at which the hydraulic switch is switched on and off is deviated or the hydraulic switch fails to operate properly. Then, according to the invention, abnormalities of the hydraulic switch can also be detected based on the above determination.
In addition, in the invention, in the event that the frictional engagement element is used as a clutch for a transmission for controlling speed changes of a vehicle or as a brake, the detection of engagement of the frictional engagement element by the engagement detection unit is implemented with the vehicle being at halt, the brakes of the vehicle being applied and an engine of the vehicle being in an idle state. Furthermore, in a construction in which a torque converter is disposed at an input portion of the transmission in such a manner as to be connected to an output shaft of the engine and in which a transmission mechanism whose actuation is controlled by the frictional engagement element is provided in such a manner as to be connected to an output side of the torque converter, it is preferable that abnormalities are detected with the abnormality detecting apparatus according to the invention.
According to a further aspect of the invention, there is provided a method for detecting the existence of an abnormality of a linear solenoid valve for regulating based on a control signal an engagement control oil pressure which is supplied to a frictional engagement element adapted to be brought into engagement upon receipt of an oil pressure force using a hydraulic switch set to be switched on and off when an oil pressure variation is applied thereto which overpasses a predetermined switching oil pressure, wherein the hydraulic switch is disposed at a position to receive the control oil pressure that has been regulated by the linear solenoid valve and is set to be switched on and off at an engagement control oil pressure at which the frictional engagement element starts to be brought into engagement and which acts as the switching oil pressure. The method comprises the steps of sending a control signal to the linear solenoid valve to increase the engagement control oil pressure from a predetermined lower pressure which is lower than the switching oil pressure to a predetermined higher pressure which is higher than the switching oil pressure, while the above step is being implemented, detecting a first pressure-increased side signal oil pressure which corresponds to the control signal resulting when the hydraulic switch is switched on and off upon receipt of the engagement control oil pressure which has been regulated by the linear solenoid valve, sending a control signal to the linear solenoid valve to decrease the engagement control oil pressure from the predetermined higher pressure to the predetermined lower pressure, while the above step is being implemented, detecting a first pressure-decreased side signal oil pressure which corresponds to the control signal resulting when the hydraulic switch is switched on and off upon receipt of the engagement control oil pressure which has been regulated by the linear solenoid valve, whereby the linear solenoid valve is diagnosed as being abnormal when a difference between the first pressure-increased side signal oil pressure and the first pressure-decreased side control oil pressure exceeds a first abnormality determination value.
The above abnormality detecting method may comprise further the steps of detecting an engagement of the frictional engagement element when making the linear solenoid valve implement the regulation of the engagement control oil pressure by sending a control signal to the linear solenoid valve to increase the engagement control oil pressure from the predetermined lower pressure to the predetermined higher pressure, detecting a second pressure-increased side signal oil pressure which corresponds to the control signal resulting when the engagement of the frictional engagement element is started, whereby the hydraulic switch is diagnosed as being abnormal when a difference between the first pressure-increased side signal oil pressure and the second pressure-increased side signal oil pressure exceeds a second abnormality determination value.
The above abnormality detecting method may comprise further the steps of detecting an engagement of the frictional engagement element when making the linear solenoid valve implement the regulation of the engagement control oil pressure by sending a control signal to the linear solenoid valve to decrease the engagement control oil pressure from the predetermined higher pressure to the predetermined lower pressure, detecting a second pressure-decreased side signal oil pressure which corresponds to the control signal resulting when the release of the frictional engagement element is started, whereby the hydraulic switch is diagnosed as being abnormal when a difference between the first pressure-decreased side signal oil pressure and the second pressure-decreased side signal oil pressure exceeds a third abnormality determination value.
According to the abnormality detecting method of the invention which is constructed as has been described heretofore, the existence of abnormalities of the linear solenoid valve can be detected easily using the relatively inexpensive hydraulic switch (without using the oil pressure sensor for detecting the value of an oil pressure). In addition, in many cases, the hydraulic switch is provided on the hydraulic device such as the change-speed control valve of the automatic transmission, and in such a case, the detection of abnormalities can be implemented using the hydraulic switch easily without selecting any specific place for the detection. Furthermore, abnormalities of the hydraulic switch can be detected easily by obtaining the signal oil pressure when the engagement or release of the frictional engagement element is started.